Level-correction device for ordnance



- 4 Sheets-Sheet 1 A. L. PERHAM LEVEL CORRECTION DEVICE FOR ORDNANCEFlled June 8. 1923 Feb. 19 1924:

c O A. 2 3 3 INST?? UMENTKL A. L. PERHM i LEVEL CORRECTION DEVICE FORORDHANCE Feb. 19, 1924 Filed. June 8, 1923 4 Sheets-Sheet z \\l rv A v.O HU Al? feb. 19, 1924. v1,484,1@344 A. l.. PERHAM I 4:Jg-:vlanCORRECTION DEVICE fon onnNANcE Fild-'June 8. 1923 A4 sheets-snee; :y

'mum Hl Ylmlmumh I Febr 199 1,454,274 A. L. PERI-AM LEVEL COIRRECTIONDEVICE FOR QRDNANGE 'l Filed, June 8; 1923 4 Sheets-Sheet L PatentedFeb. 19, 1924.

UNITED STATES 1,484,274 PATENT OFFICE;

ARTHUR LEONARD PERHAM, OF EAST MOSELEY, ENGLAND, ASSIGNOR T0 VICKERSLIMITED, 0F WESTMINSTER, LONDON, ENGLAND.

LEVEL-CORRECTION DEVICE FOR ORDNANCE.

Application filed .Tune 8,

To all w hom it may concern.

Be it known that I, ARTHUR LEONARD PERHAM, a subject of the King ofGreat Britain, residing at The New House, Matham Road, East Moseley, inthe county of Worcester, England, have invented certain new and usefulImprovements in or Relating to Level-Correction Devices for Ordnance, ofwhich the following is a speciiication.

This invention relates to level correction devices for ordnance,particularly guns for anti-aircraft or coast defence mounted on portableor automobile carriages. Such gun carriages are often required to beplaced on ground that does not afford a level or constantly rigidsupport, and it is necessary for accurate shooting to provide means forlevelling the gun mounting itself so as to bring the training axis intoa truly vertical position, or for adjusting the sighting apparatus tocompensate for the inclination of the training axis of the gun from thevertical. If the gun is other than a very light one it is notpracticable, owing to the weight of the parts, to provide means formaintaining its training axis vertical, and the object of the presentinvention is to provide an improved correction device by which errors inthe aiming of the gun due to the lack of level of the gun carriage canbe neutralized or compensated for without the gun mounting itselfrequiring to be levelled.

In gun mountings to which the invention is particularly applicable, thegun is usually laid in elevation and training by means of pointers orother members set to scales of elevation (or range) and of angles otraining; alternatively the said pointers are arranged to turn on axesconcentric with other pointers under the control of a distant sightingapparatus on the well known followthe-pointer77 system, or a pointer(one for elevation and one for training) under the conjoint influence ofthe distant sighting apparatus and the gun may be employed, the pointerbeing maintained opposite a fixed mark as is well understood.

According to the invention the pointer or other member by which the gunis laid either in elevation or in training is connected to a spiritlevel or its equivalent in such a manner that when the level is broughthorizont-al an adjustment will be given to the pointer so as tocompensate for the er- 1923. Serial No. 644,118.

ror due to the tilt of the training axis. For example, in the case ofelevation the gun elevat-ion dial might be arranged to rotate once forG0o of gun elevation. In this case the level would be coupled to the gunele.- vation pointer so that each degree of angular movement of thelevel would eli'ect 6 of angular movement of the said pointer. In thecase of the gun training pointer, the level correction is appliedthrough a variable-ratio device the ratio of which is adjusted inaccordance with the gun elevation. This is necessary because the lateralerror due to the inclination of the gun trunnions varies with the angleof gun elevation. At 45" of gun elevation the inclination of thetrunnions requires a training correction of an amount equal to thisinclination and at higher or lower elevations the correction isincreased or reduced in proportion to the tangent of the angle of gunelevation.

By the use of the invention as hereinbefore described guns may be laidin accordance with angles transmitted from a distant or separatesighting station without the lack of level oi" the mountings introducinginaccuracy in the shooting, but it is necessary that at every angle ofgun training the levels appertaining to the gun elevation pointer andthe gun training pointer should be readjusted, because the effect of atilted training axis varies with the training angle of the gun asmeasured from the direction in which the axis is tilted. To obviate thenecessity for such continual adjustment of the levels, the levels may beconnected to crossheads free to slide in directions at right angles toeach other, in which crossheads a crank pin engages. If this crank pinis adjusted in radius to correspond with the angle of inclination of thetraining axis and if it is adjusted relatively to the angle of guntraining so that the rotation of the member carrying it is in phase withthe angles of the gun training in relation to that angle of training inwhich the training axis is tilted, then at all angles of training thelevels will be adjusted automatically by the crank pin to gun trainingthe two levels are adjusted to a horizontal position the two crossheadsWill cause the crank pin to take up a position on the said rotatablemember corresponding to the amount and direction of the tilt ot the guntrainingaxis. If the crank pin is now locked to the rotatable member,then at all training angles it Will keep the tivo levels horizontal.

The invention is also applicable to gun sighting apparatus that iscombined with the gun mounting, its mode ot application varying with thetype of sighting apparatus in use. As applied to gun sighting apparatuscombined with the mounting it is generally only the training thatrequires correction and the invention Would then be applied to thelateral deflection dial.

A common type of levelling arrangement is that in which the sightingapparatus is pivoted about an axis parallel to the axis of the gun andis levelled about this axis. Such a levelling arrangement is open to theobjection that relevelling is necessary with every change in guntraining and to avoid this necessity the automatic levelling teature ofthe invention can be applied to such devices. For example a crank pincan be positioned by the two levels and erossheads as hereinbetoredescribed and be so connected to the sighting apparatus that during thetraining of the gun the said crank will automatically level the sightingap paratus about its axis parallel to the axis ot' the gun.

In order that the said invention may be clearly understood and readilycarried into effect, the same Will now be described more fully withreference to the accompanying drawings, in Whichz Figure l is a sideelevation shewing diagrammatically a simple lorm of the cor rectiondevice applied to the elevation pointer of a gun,

Figure 2 is a section taken approximately on the line 2, 2 of Figure 1,

Figure 3 is a side elevation shewing diagrammatically a form of thecorrection device applied to the elevation and train ing pointers of agun, in conjunction with an arrangement by which the corrections areeffected automatically at all angles of elevation and training so longas the tilt of the training axis remains the same,

Figure 4 is a section taken approximately on the line 4f, 4 of Figure 3,

Figure 5 is a front elevation of part of Figure 3,

Figure 6 is a view similar to Figure 3 shewing the correction deviceemployed for automatically levelling a gun sight, and

Figure 7 is a rear elevation of Figure 6.

Referring first to Figures 1 and 2, A represents the elevation dialconnected to a pinion a meshing With the elevating rack a' of the gun, Brepresents the reader or pointer associated With this dial and Crepresents the level the support C ot which is pivoted at c to a bracketc on the gun carriage and has a toothed segment C2 meshing with a pinionb connected to the pointer B. It is essential that the same gear ratioshall exist between the support C and the pointer B as exists betweenthe gun and the dial A. It Will therefore be seen that if the trainingaxis of the gun is inclined to the vertical in a direction affect-ingthe correct elevation of the gun, the bringing of the level C to thehorizontal will vary the position ot' the pointer B by an amountsuiiicient to compensate for the elevation error caused by the tilt ofthe training axis at the particular angle ot' training existing at themoment. It the angle of tilt remains constant and the angle of trainingis altered, the level C will require readjustment to maintain ithorizontal in this particular construction. A similar arrangement may beemployed in conjunction with the training pointer (the level beingsituated at right angles horizontally to the level C) but in this easethe correction is applied from the level carrier to the training pointerthrough a variable-ratio device, such as is hereinafter described, theratio of which is adjusted in accordance with the gun elevation for thereason hereinbefore referred to.

In the construction shewn by Figures 3, 4 and 5 the elevation dial A andthe pointer B are geared to the elevating rack a of the gun and to thelevel support C respectively in substantially the manner described withreternce to Figures l and 2. The level sup port C is adjusted about itspivot c by a bar D which is free to slide vertically in guides andcarries at its lower end a crosshead (Z. This crosshead can be adjustedvertically by means of a haudwheel D and pinion rl, the latter gearingwith rack teeth ou the bar D. Another level E (Figure 5) at right anglesto the level C in the horizontal plane, is carried by a support Epivoted at c on the gun carriage. This level adjusted about it pivot byabar F through a bell crank lever Fx and a link f". The said bar is freeto slide horizontally in guides and carries at one end a erosshead fwhich can be adjusted horizontally in a similar manner to the crossheadZ by means of a handwheel F and pinon f. The said crossheads engage witha pin g in the centre of a disc G (Figure 4). This pin passes throughthe disc and en ages 0n the other side With triction discs The discs Gand G are assembled in alternate layers with friction Washers g. TheWhole thus assembled is contained in a casing G2 by means of a cover g2which exerts sutiicient pressure between the various contacting faces tofrictionally grip the crank pin disc G in any Wart-ffl uw:

desired position to which it is set by means of the handwheels D and F.The casing G2` is suitably geared to the training rack of the| gunmounting so that it rotates with, and at the same angular velocity as,the mounting. The pin g thus conveys motion, by reason of itseccentricity, through the crosshead d and the bar D to the pointer B ofthe elevation dial A, and through the crosshead f and the bar F to thebar H of a variable-ratio device and thence to a differential gear z,which operates the pointers H of a training receiver.

The aforesaid variable-ratio device through which the corrections aremade to the pointers H of the training receiver is necessary on accountof the fact that the lateral error due to the inclination of the guntrunnions varies With the angle of the gun elevation. Therefore, theamount of correction applied must be variable accordingly. This islobtained as follows The bar H is supported by a pin h2 in the extensiono-f a rack H2 operating upon the differential gear L and has a movablefulcrum h3 which is capable of being set to a scale Ha of gunelevations. The lower end of the said bar is forked and engages with alpin f2 on the bar F. The latter bar in its backward and forwardmove-ments oscillates the bar H about its fulcrum f1.3 and transmitsmovement to the rack H2 varied in magnitude according to the gunelevation, i. e., according to the position of the fulcrum h3 relativelyto the pins h2 and f2. It will be seen that by the operation of the twohandwheels D', F each level is brought to the horizontal, the resistanceof the friction plates G', g overcome, and the crank pin g by thisoperation correctly positioned according to the amount and direction ofthe tilt of the training axis so that the correct compensation will begiven to the pointers B and H at all angles of training. Should theoperator notice that the levels are no longer maintaining the horizontalposition during change of the angle of training, then he knows that theinclinationA of the training axis has changed and he again adjusts thelevels to the horizontal by the handwheels D and F thereby impressing anew setting upon the crank pin g to suit the changed conditions of tilt.The duty of the operator is merely one of supervison of the levels andre-adjustment of them as necessary. The fact that the levels and theoperator move with the gun in training is an advantage that theinvention possesses over mountings in which the axis of training isitself adjusted to the vertical position.

When the invention is used in conjunction with an elevation receiveradjustable from a distant station in accordance with the angles ofelevation to be given to the gun, the bar D of Figures 3 to 5 and thelevel support C of Figures 1 and 2 would be connected to the equivalentof the pointer B through a differential gear.

In Figures 6 and 7 K is the gun sight the bracket L' of which isconnected to a shaft K rotatably supported in bearings 7c', lc on thegun cradle so that the said shaft lies parallel to the axis of the gunat all angles of elevation. In employing the automatic arrangement shewnin Figures 3 to 5 for rocking the shaft K the following modificationsare made, the same reference letters as are used in Figures 3 to 5 beingalso used for similar parts in Figures 6 and 7. The level support C hasa slotted end with which a pin d* on the bar D engages, the levelsupport E also has a slotted end with which a pin f* on the bar Fengages and the casing G2 (together with the parts contained therein) isarranged horizontally instead of vertically as in Figures. 3 to 5. Theelevation dial A and pointer B are dispensed with, the bar D beingmerely employed for the purpose of assisting in the correct positioningof the crank pin g. The pivot pin e of the level support E is rigid withthe latter and extends forwardly through a bearing E2 on lthe guntrunnion. This extension of the pivot pin is made to form one half of aHookes joint E3 the other half of which forms part of the aforesaidshaft K. The axis of the pivotal connection e3 of this universal jointis arranged to be in alignment with the axis of the gun trunnions. Inoperation, the two levels having been adjusted by their respectivehandwheels and the crank pin g set to its correct position relative tothe angle of training in which the vertical axis of the mounting istilted and to the magnitude of such tilt` the pivot pin e is always keptcross levelled by the movement of the bar D and this correction istransmitted through the Hookes joint E3 to the gun sight. So long as thegun is kept horizontal and the sight and the shaft K therefore parallelto the pivot pin e, both halves of the Hookes joint will move togetherand through the same angle, but as the gun is elevated the shaft K moveswith it whilst leaving the pivot pin e in its original position. Themovementimparted to the gun sight through the Hookes joint is thereforeincreased in the inverse proportion of the cosine of the angle ofelevation. In this manner the Hookes joint functions as a variable-ratiodevice and with the added correction derived from the range setting ofthe sight replaces the variable-ratio device described in connectionwith Figures 3 to 5.

What I claim and desire to secure bv Letters Patent of the United Statesis l. A level correction device for ordnance, comprising in combina-tiona member by which the gun is laid, a levelling element and a connectionbetween said member and said elementoperating to adjust said member tocompensate for the error due to the tilt of the training axis of thegun.

2. A level correction device for ordnance, comprising in combination amember by which the gun is laid in elevation, a levelling element and aconnection between said member and said element operating to adjust saidmen'iber to compensate for the elevation error due to the tilt of thetraining axis of the gun.

3. A level correction device for ordance, comprising in combination amember by which the gun is laid in training, a levelling element and aconnection between said member and said element operating to adjust saidmember to compensate for the training error due to the tilt of thetraining axis of the gun.

4. A level correction device for ordnance, comprising in combination amember by which the gun is laid in elevation, a member by which the gunis laid in training, a levelling element, a connection between saidlevelling element and the first mentioned member, a second levellingelement, and a connection between the latter levelling clement and thesecond mentioned member.

5. A level correction device for ardnance, comprising in combination anelevation indicator composed of two movable members, mechanism foroperating one of said members in accordance with the elevating movementsof the gun, a levelling element and mechanism interposed between saidelement and the other member of the indicator, the last mentionedmechanism having the same gear ratio as that of the rst mentionedmechanism.

G. A level correction device for ordnance, comprising` in combination amember by which the gun is laid in training, a levelling element.lconnections between said member and said element and a variable ratiodevice forming part of said connections.

7. A level correction device for ordnance, comprising in combina-tion amember by which the gun is laid in training, a levellingr element,connections between said member and said element, a fulcrnmed leverforming part of said connections and means for adjusting said fulcrum toagree with the gun elevation.

8. A level correction device for ordnance, comprising in combination amember by which the gun is laid in elevation, a member by which the gunis laid in training, a levellingr element, a connection between saidlevelling element and the first mentionel member, a second levellingelement, a connection between the latter levelling element and thesecond mentioned member, and means for automatically maintaining saidelements in their levelled position during the training of the gun solong as the tilt of the training axis of the gun remains unaltered.

9. A level correction device for ordnance, comprising in combination amember by which the gun is laid in elevation, a meniber by which the gunis laid in training, a levelling element, a connection between saidlevelling element and the first mentioned member, a second levellingelement, a connection between the latter levelling element and thesecond mentioned member, an adjustable member, means for connecting saidadjustable member to said levelling elements and means for rotating saidmember in synchronism with the training of the gun.

l0. A level correction device for ordnance, comprising 'in combination amember by which the gun is laid in elevation, a member by which the gunis laid in training, a levellingwelement, a connection between saidl=`levelling@eleinenti/ and the first mentioned imem'ber, a secondlevelling clement, a connection between the latter levelling element andthe second mentioned member, a crank pin, a member carrying said crankpin, guided bars connected to said levelling elements, said crank pinengaging in slots formed in said bars at right angles to the paths ofmovement of the latter, and means for rotating said member insynchronism with the training of the gun.

l1. A level correction device for ordnance, comprising in combination amember by which the gun is laid in elevation, a member by which the gunis laid in training, a levelling element, a connection between saidlevelling element and the first mentioned member, a second levellingelement, a connection between the latter levelling element and thesecond mentioned member, a crank pin, a member carrying said crank pin,guided bars connected to said levelling ele ments, said crank pinengaging in slots formed in said bars at right angles to the paths ofmovement of the latter, a further member, means for rotating the lattermember in synchronism with the training olf the gun and means forfrictionally holding the last two mentioned members in operativeconnection with each other.

l2. A level correction device for ordnance, comprising in combinationwith the gun sight, two levelling elements arranged to move in verticalplanes at right angles to each other, means for automaticallymaintaining said elements in their levelled position during the trainingof the gun so long as the tilt of the training axis of the gun remainsunaltered and means operated by the first mentioned means for rockingthe sight about a longitudinal axis parallel to the axis of the gunbarrel.

13. A level correction device for ordnance,

comprising in combination with the gun sight, tWo levelling elementsarranged to move in vertical planes at right angles to each other7 anadjustable member, means for connecting said member to said levellingelements, means for rotating said member in synchronism with thetraining of the gun and means whereby the rotation of Said memberautomatically rocks the sight about a longitudinal axis parallel to theaxis of 10 the gun barrel.

ARTHUR LEONARD PERHAM.

Witnesses BAsIL MARSH, S. MAnsH.

